Brain Development

Experience-Expectant Plasticity

The mechanism of brain development where the brain relies on normal experiences expected in the environment to shape its growth and prepare it to learn.

Neural Darwinism

The evolutionary process in brain development wherein synapses that are frequently activated are preserved, while inactive ones are pruned.

Synaptic Pruning

The process occurring during the first $12$ years of development that removes unused synaptic connections to make the brain more efficient.

Brain Efficiency

An improvement in processing speed and logical capability resulting from the pruning of unused synapses in the brain.

Touch and Stimulation

Critical environmental inputs that play a central role in experience-expectant brain plasticity and synaptic pruning.

Brain-Building Through Play

Interactive activities for infants, toddlers, and children designed to promote brain growth, including the $5$ steps for serve and return.

Serve and Return

A $5$-step interactive brain-building process between a child and caregiver that shapes brain architecture through back-and-forth interaction.

Cerebellum Growth in Infancy

The tripling of the cerebellum during the first $12$ months of life, which is directly related to rapid motor skill development.

Infant Auditory Preference

An infant's tendency to prefer the mother's voice and detect subtle aspects of language more acutely than adults during the first few months.

Primary Language Wiring

The structural adaptation of the brain through experience that reinforces pathways for the primary language while initiating pruning for non-native languages.

Infant Visual Development

The transformation of initial dim and limited sight into full binocular vision, which is connected to depth perception and locomotion.

Newborn Face Recognition

The innate capacity of newborns to recognize and prefer human faces, which continues to improve alongside hippocampus growth.

Hippocampus Growth in Infancy

The developmental expansion of the hippocampus, a brain region related to memory that aids in improving facial recognition.

Year Two Brain Growth

A phase in toddlerhood characterized by ongoing pathway formation, complex task development, and a major increase in the rate of myelination.

Myelination in Toddlers

The process of coating nerve pathways that accelerates during year two, enabling the brain to execute higher-order, complex tasks.

Vocabulary Explosion

A dramatic surge in language acquisition during toddlerhood where vocabulary increases by $4\times$ between ages $1$ and $2$.

Higher-Order Cognitive Abilities in Toddlers

Emerging psychological capabilities during the second year, including self-awareness, improving attention, and basic emotional skills.

First Window of Opportunity

The developmental period from ages $0\text{ to }3$ years characterized by rapid early brain development and foundational learning.

Second Window of Opportunity

The developmental stage during early adolescence (ages $9\text{ to }14$) characterized by rapid brain remodeling, vulnerability, and learning potential.

Biological Stressors in Adolescence

Hormonal changes that impact the structural and functional development of neurobiological circuits in the adolescent brain.

Population-Level Stressors

External shocks or disasters affecting whole populations that can result in greater or longer-lasting impacts on adolescents.

Social Stressors in Adolescence

Environmental factors requiring a supportive context for adolescents to establish social identity and handle peer pressure.

Frontal Lobe Gray Matter Reduction

A decrease in frontal lobe gray matter during adolescence caused by synaptic pruning, leading to improved logic and processing speed.

White Matter Expansion in Adolescence

An increase in myelination during adolescence that facilitates efficient message transmission between the brain and the environment.

Prefrontal Cortex

The brain region responsible for cognitive control, logic, reasoning, and decision-making, which matures at a slower rate than emotional networks.

Prefrontal Cortex Maturation Timeline

The extended developmental trajectory of the prefrontal cortex, which remains under construction until the mid-$20$s.

Cognitive Control Network

The frontal lobe network involved in behavioral control, logic, and reasoning, which develops at a slower pace than the socioemotional network.

Socioemotional Network

The brain network governing emotions and responses to dopamine and peer influence, which develops faster than the Cognitive Control network.

Dopamine

A neurotransmitter triggered by pleasurable or emotionally arousing events that heightens the Socioemotional network and inhibits the Cognitive Control network.

Dopamine Flooding in Adolescence

The neurological reaction occurring when adolescents spend time with peers, leading to heightened socioemotional activity and reduced cognitive control.

Adolescent Risky Behavior

Behavior resulting from an imbalance where dopamine heightens an earlier-maturing Socioemotional network while inhibiting an underdeveloped Cognitive Control network.

Delayed Phase Preference

A puberty-driven shift in biological pressure that changes sleep timing (feeling sleepy vs. active) without reducing total required sleep hours.

Adolescent Sleep Duration

The required amount of sleep for adolescents, which remains at $8\text{ to }9$ hours per night despite shifts in sleep timing.

Melatonin Level Changes

Biological shifts in melatonin secretion during puberty that alter the circadian cycle and sleep patterns in adolescents.

Later School Start Times Policy

An intervention designed to align school schedules with adolescent delayed phase preference and circadian shifts to save lives.

Plasticity

The brain's capacity to be shaped by experience and its fundamental preparedness to learn.

Binocular Vision Development

The maturation of dual-eye coordination in infancy that provides depth perception and supports locomotion development.

Peer Influence Responsiveness

The heightened sensitivity of the adolescent Socioemotional network to social interaction and peer presences.

Cognitive Control Network Inhibition

The temporary suppression of logic and decision-making centers caused by dopamine release during emotionally arousing social events.

Under Construction Until 25

The principle that prefrontal brain regions governing executive function and decision-making continue developing until around age $25$.